Machine for grinding flutes



May 24, 1938. s. w. BATH ET AL MACHINE FOR GRINDING FLUTES Filed June 1, 1936 10 Sheets-Sheet 1 May 24, 1938. s. w. BATH ET AL MACHINE FOR GRINDING FLUTES l0 Sheets-Sheet 2 Filed June 1, 1936 jyezru dzwge 77. 79%

May 24, 1938. s. w. BATH ET AL MACHINE FOR GRINDING FLUTES l0 Sheets-Sheet 3 Filed June 1, 1936 ru F u m May 24, 1938. s. w. BATH ET AL MACHINE FOR GRINDING FLUTES 10 Sheets-Sheef. 4

Filed June 1, 1936 May 24, 1938. s w, BATH ET AL 2,118,139

MACHINE FOR GRINDING FLUTES Filed June 1, 1936 10 Sheets-Sheet 5 +205 i r w I "T ff-l 12 L j" J- i J .141 1 1 1m y 938. s. w. BATH ET AL 2,118,139

MACHINE FOR GRINDING FLUTES Filed June 1, 1936 '10 Sheets-Sheet 6 withdre May 24, 1938. s. w. BATH ET AL MACHINE FOR GRINDING FLUTES l0 Sheets-Sheet 7 Filed June 1, 1936 May 24, 1938. s. w. BATH ET AL 2,118,139

MACHINE FOR GRINDING FLUTES Filed June 1, 1936 10 Sheets-Sheet 8 y 1938. s. w. BATH ET AL 2,118,139

MACHINE FOR GRINDING FLUTES Filed June 1, 1936' 10 Sheets-Sheet 9 y 1938. s. w.- BATH ET AL 2,118,139

MACHINE FOR GRINDING FLUTES Filed June 1, 1936 10 Sheets-Sheet l0 EJ976675. d 2 91/8? fhA'aZAc kley Patented May 24, 1938' UNITED STATES PATENT orncr:

MACHINE FOR GRINDING FLU'I'ES Massachusetts Application June 1, 1936, Serial No. 82,808

16 Claim.

This invention relates to the manufacture of taps for threading holes in metal, and relates more particularly to the finishing of the longitudinal flutes in such'taps or in other similar articles.

It is customary to rough out these flutes with a milling cutter before the taps are hardened and to finish the flutes by grinding after the hardening operation.

It is the general object of our invention to provide an improved machine for performing the flute-grinding operation.

In the preferred form, our improved machine is hydraulically actuated, and important features of our invention relate to novel devices by which the operator may conveniently vary and control the operation of the machine through manipulation and adjustment of the hydraulic mechanism.

Our invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawings, in which Fig. l is a front elevation of our improved flutegrinding machine;

Fig. 2 is a partial right-hand elevation, looking in the direction of the arrow 2 in Fig. 1;

Fig. 3 is an enlarged front elevation of certain control mechanism;

Fig. 4 is a sectional plan view, taken along the line 4-4 in Fig. 3;

Fig. 5 is a front elevation of a cam and cam plate to be described; Fig. 6 is a sectional plan view, taken along the line 6-6 in Fig. 1;

Fig. 7 is a partial front elevation, looking in the direction of the arrow 1 in Fig. 6;

Fig. 8 is a detail side elevation, looking in the direction of the arrow 8 in Fig. 6;

Fig. 9 is a plan view of certain parts,'par'tly in section, and looking in the direction of the arrow 9 in Fig. 3;

Fig. 10 is a sectional front elevation, taken along the line Iii-40in Fig. 9;

Fig. 11 is a right-hand side elevation of certain parts, looking in the direction of the arrow II in Fig. 9;

50 Fig. 12 is a left-hand detail side elevation, looking in the direction of the arrow l2 in Fig. 9;

Fig. 13 is a detail sectional view showing a speed control valve and taken along the line l3-l3 in Fig. 11;

55 Figs. 14 and 15 are views similar to Fig. 13 but showing the valve in successive difierent positions;

Fig. 16 is a sectional front elevation of certain valve control mechanism shown at the right in Fig. 1;

Fig. 17 is a side elevation of the control mechanism, looking in the direction of the arrow I! in Fig. 16;

Fig. 18 is a left-hand side elevation of the tableelevating mechanism, looking in the direction of 10 the arrow iii in Fig. 1;

Figs. 19 and 20 are front elevations of parts of said mechanism, looking in the direction of the arrows l9 and 20 respectively in Fig. 18;

Fig. 21 is a detail plan view, looking in the di- 15 rection of the arrow 2| in Fig. 19;

Fig. 22 is an end view, looking in the direction of the arrow 22 in Fig. 21;

Fig. 23 is a sectional plan view of the work spindle head, looking in the direction of the arrow 20 23 in Fig. 1;

Fig. 24 is a. sectional side elevation, taken along the line 24-24 in Fig. 23;

Fig. 25 is a detail side elevation, looking in the 1 direction of the arrow 25 in Fig. 23; 25

Fig. 26 is a'side elevation, partly in section, of certain index valve mechanism, looking in the direction of the arrow 26 in Figs. 1 and 27;

Fig. 27 is a sectional front elevation, partly broken away and taken along the line 2l2| in 30 Fig. 6;

Fig. 28 is a view similar to Fig. '27 but showing certain parts in a different position;

Fig. 29 is a front elevation of the index valve disc; 35

Fig: 30 is a side elevation thereof, looking in the direction of the arrow 30 in Fig. 29;

Fig. 31 is a diagrammatic view showing the hydraulic connections; and

Figs. 32 to 35 inclusive show successive steps 40 in a flute-grinding operation.

Referring to Figs. 1 and 2, our improved flutegrinding machine comprises a frame 40 having a wheel head 4! mounted in fixed position thereon and supporting a grinding wheel W on a wheel 45 spindle 42. The wheel spindle may be rotated by any suitable driving mechanism, such as an electric motor or belt and pulley connection (not shown).

Vertical adjustment of work A bracket 44 (Fig. 2) is siidable in guideways 46 on the front of the frame 40 and is movable vertically by a screw 46 rotatable in fixed bearings and threaded through a nut 41 fixed on the provided with a crank arm 59 and handle '89. By

turning the handle 98, the screw 48 may be rotated. As the screw is held in fixed vertical position, the nut 41 and bracket 44 will be correspondingly raised or lowered.

The handle 84 is used for major adjustments of the work-supporting bracket 44, but for finer adjustments, particularly during the grinding operation, we provide an additional crank arm 1 (Figs. 18 and 19) which is loosely mounted on t e outer end of the shaft 89.

The hub 88 of the crank arm 51 is provided with an offset axially extending bearing 99 for a plunger 69 having a toothed plate 8| (Fig. 22) secured to its outer end "and slidable between guiding projections 92 (Fig. 21) formed on the offset bearing 59.

A coil spring 93 (Fig. 19) is mounted in a pocket in the crank arm and normally forces the plunger 89 to the right in Fig. 19, causing the teeth on the plate 9| to engage the teeth of the gear 92 which is fast on the shaft".

The crank arm 91 is thus normally connected direct to the gear 92 and shaft 99. Provision is made, however, for disengaging the toothed plate 8| from the gear 92 when it is desired to make a substantial adjustment in the position of the bracket 44 by means of the crank handle 89.

For this purpose a bell crank 94 (Fig. 19) is pivoted at 65 on a projection of the bearing 59, and is connected by a link 98 to a handle lever 91, which is pivoted at 68 to the upper end of the crank arm 91. By moving the handle portion 99 of the lever 91 downward, the bell crank 94 may be caused to withdraw the plunger 99 against the pressure of the spring 93, thus disengaging the toothed plate 6| from the gear 92. As soon as the handle portion 99 is released, however, the plate and gear will be reengaged. The use of the handle 69 during the grinding operation will be hereinafter explained. I

A bed 19 (Figs. 2 and 19) is siidable forward and rearward along guideways on the top surface of the bracket 44. An adjusting screw 1| is rotatable in a bearing 12 at the front of the bed 19 and is provided with a hand-wheel 13. The screw 1| is threaded in a nut 14 on the bracket 44. Forward and rearward manual adjustment of the bed 19 is thus made easily available.

A work table 19 is slidable transversely of the machine along guideways 19 and 15' (Fig. 2) on the bed 19. The work table" (Fig. 31) is connected by a piston rod 18 to a piston 18 siidable in a main hydraulic cylinder 11 shown in end view in Fig. 2. Pipes 18 and 19 (Fig. 31) connect the cylinder 11 to hydraulic supply and control mechanism to be described.

Work spindle head The tap T to be ground is mounted on the sliding work table 15 between a fixed tail center 89 (Fig. 32) and a head center 8|. The head center 9| (Fig. 23) is mounted in the end of a work spindle 82 siidable and rotatable in a bearing in the work spindle head 93 which is mounted on the sliding table 15 and which is adjustable l ngitudinally of the table as indicated at 84 in Fig. 24.

A coil spring 85 is mounted on a reduced portion 89 of the plunger" and pushes the plunger to the right in Fig. 23 until the head center 8| engages the work or until a collar 81 on the plunger portion 88 engages the rear end of the plunger bearing.

A hand lever 48 is pivoted at 99 on the plunger bearing and extends upward therefrom. The lower end of the lever 88 is forked as indicated at 99 (Fig. 24) and engages the inner face of the collar 81 previously described. By pressing the handle 88 to the right in Fig. 23, the head center 8| may be withdrawn to permit insertion or removal of the work. A dog or driver 92 (Figs. 23 and 25) is mounted on an enlarged portion of the head center 8| and is notched as indicated at 93 to loosely receive the shank of a tap T.

Indexing mechanism For the purpose of indexing the work, the head center 8| or the work spindle 82 is provided with a pinion 88 (Fig. 23) meshing with a gear 99 mounted on a counter shaft 91 rotatable in a fixed bearing in the work head 83. At its opposite end the countershaft 91 is provided with a ratchet wheel 88, the teeth of .which are engaged by a pawl 99 pivotaily mounted on an index lever I99, which in turn is loosely pivoted on the outer end of the countershaft 91.

The feed lever I99 is provided with a stud I9I (Fig. 24) extending through an elongated slot I92 in the upper end of an actuating lever I93 pivoted at I94 on the work spindle head 83.

A piston rod I95 and piston I96 are siidable in an index cylinder I91, and the piston rod is connected by a slotted head I98 and cross-pin I99 to the index lever I93, with the cross-pin extending through a second slot 9 in the index lever.

Pipes III and H2 connect the opposite ends of the cylinder I91 to an index valve mechanism 4 (Fig. 1) mounted on the front side-of the bracket 44 and connected by a pipe I I5 (Fig. 31) to a high pressure supply pipe II6 which in turn is connected to a pressure pump P.

A shut-off valve H1 is preferably provided in the pipe II! for a purpose to be described. The valve mechanism 4 is also provided with an exhaust pipe II8 through which liquid may be discharged to a reservoir 8.

The index valve mechanism I I4 is shown in detail in Figs. 26 to 30 and comprises a casing-in which is rotatably mounted a disc I29 having an arcuate recess I2I in one face thereof and having smaller recesses I22 and I23 in the same face but provided with ports I24 and I25 extending through the disc from opposite ends of the recesses I22 and I23.

The disc I29 is mounted on a short shaft I29 rotatable in a bearing I21 formed on the casing of the valve mechanism. The shaft I29 is provided at its outer end with an arm I28 (Fig. 1) extending upward into the path of index dogs I29 and I39 adjustably secured in a T-slot I3| in the front of the sliding table 15. I

The exhaust pipe II9 (Fig. 27) is connected to a port I32 which communicates with the arcuate recess |2| in all working positions of the disc I29. The pipes I II and H2 are also provided with ports I33 and I34 respectively and the supply pipe H5 is connected to a recess I35 (Fig. 26) behind the disc I29 and in constant communication with the ports I24 and I25.

When the index valve disc I29 is in the position shown in Fig. 27, the supply pipe II 5 'is connected through the port I25, recess I23 and the port I34 to the index cylinder pipe II2, thus giving the indexing mechanism an operating or feeding movement.

At the same time, the pipe I II from the opposite end of the cylinder is connected through the port I33, arcuate recess I2I and port I32 to the exhaust pipe II8. At this time the port I24 and recess I22 are out of alignment with the port I33.

When the valve disc I20 is shifted to the position shown in Fig. 28, the supply pipe is connected through the port I24, recess I22 and port I33 to the pipe III, which thus supplies oil under pressure at the right-hand end of the index cylinder I0'I (as viewed in Fig.24) and gives the feeding mechanism an idle return stroke; At the same time, the pipe H2 is connected through the port I34 and arcuate recess I2I to the port I32 and exhaust pipe II 8, while the supply port I25 and recess I23 are out of operative position.

The arm I28 is engaged by the dog I30 and shifted from the right-hand position shown in Fig. 1 to the left-hand position indicated by the broken line as the table 15 is moved to the left to withdraw the work from the wheel. At the righthand limit of table travel, when the wheel is in the flute, the arm I28 is engaged by the dog I29 and is returned to the position indicated in Fig. 1,

thus giving the indexing mechanism an idle re-* turn stroke without indexing action.

On each engagement of the arm I28 by the dog I30, the piston I06 will move to the right in Fig.

24, and the pawl 99 will engage the teeth of the,

ratchet wheel 98 and give the countershaft 91 a partial revolution which is communicated through the gear 96 and pinion 95 to' the work spindle 82, thus indexing and advancing the work angularly.

If it is desired at any time to discontinue the indexing, the valve I" (Fig. 31) may be closed, after which the arm I28 and valve disc I20 may be shifted as previously described but no indexing action will take place.

Reversing valve and speed control valve The supply of liquid to the main cylinder I1 is controlled by a reversing valve R (Fig. 31) comprising a cylinder I40 having a floating piston or bobbin I4I freely slidable therein.

The pipes I8 and I9 previously described connect ports I42 and I43 in the cylinder I 40 to the opposite ends of the main cylinder 'II which actuates the sliding table. Exhaust ports I44 and I45 in the cylinder I40 are connected through an exhaust pipe I46 to the reservoir S.

.An additional port M1 is connected through a speed-control device D (Figs. 11 and 31) to a branch supply pipe I49 which provides oil under pressure. The speed-control device D is shown in detail in Figs. 11 and 13 to 15, and comprises a throttle valve plate I5I mounted on a short shaft I52 rotatable in fixed bearings I53 and I54 (Fig. 11) and having an arm I55 secured to the front end of the shaft and provided with a handle I56 (Fig.2).

By manually adjusting the handle I 66, the throttle valve plate I5I will vary the flow of oil from the supply pipe I49 through the port I51 (Fig. 11) to the passage I58 which connects the speed control device D to the port I41 in the reversing valve mechanism R (Fig. 31) The throttle valve plate I5I may be manually adjusted to any desired position and directly controls the rate of travel of the sliding table.

The reversing valve cylinder I40 (Figs. 9 and 31) is provided with end ports I60 and I6I communicating with cross passages I62 and I63. The cross passage I62 is connected by a branch pipe I64 (Fig. 31) to a pressure supply pipe I65 which in turn communicates with the pressure pipe I49 previously described.

As substantially higher pressure is required for operation of the index mechanism, it is customary to provide a reducing valve I66 between the pipes H6 and I49 and a low pressure relief valve I61 in a branch pipe I68 connecting the pipe I49 to the reservoir S. With this arrangement, substantially lower pressure is provided in the pressure supply pipes I49, I65, and I64.

The cross passage I62 (Fig. 31) is also connected by a pipe I10 to a casing III containing a poppet valve I12 under the control of a dog I13 on the sliding table 15 (Figs. 6 and '7) through connections to be described. The casing I II is also provided with a port "4 (Fig. 31) connected to an exhaust pipe I15 communicating with the reservoir S.

The cross passage I63 at the opposite end or the reversing valve cylinder is connected through a pipe I'I6 (Fig. 31) to a second poppet valve casing I'I'I having a valve I18 under the control of a second dog I'I9 on the sliding table I5. A port I in the casing I" is connected by a'branch pipe I8I to the exhaust pipe previously described.

When the machine is in operation, both ends of the piston I4I are exposed to equal pressures. ex-

.cept as one or the other poppet valves is opened of the cylinder I40 is also connected through a passage I 83 (Fig. 31) and pipe I 84 to a chamber I85 in a poppet valve control mechanism P. A second chamber I86 in the mechanism P is connected to the pressure supply pipe I65 and a third chamber I8'I is connected by a pipe I88 to the exhaust pipe "5.

The control mechanism P is mounted on an arm I89 (Fig. 4) secured to the bed I0 and comprises a poppet valve I90 controlling communication between the chambers I86 and I85 and a second poppet valve I9I controlling communication between the chambers I85 and I81.

The parts are shown in Fig. 31 in the position assumed when the machine is at rest, with the poppet valve I90 closed to cut off pressure oil from the pipe I84 and cross passage I63, but with pressure oil supplied through the pipe I64, cross passage I62 and port I60 to move the floating piston or bobbin I4I to the left-hand position indicated in Fig. 31. At the same time the left-hand end of the cylinder I40 is connected through the passage I 83 and pipe I 84 to the exhaust pipe I98 through the open poppet valve I9I.

The detailed construction bf the mechanism P is shown in Figs. 3, 4, 16, and 17.

Springs I92 and I93 (Fig. 16) are positioned under the valves I 99 and I 9I and tend to close said valves. The stems of the valves I90 and I9I extend upward through suitable glands and are engaged at their upper ends by contact screws I94 and I95 in opposite ends of a rock arm I96, pivoted on a bracket I91 mounted on the. arm I89 as previously stated. The rock arm I96 is connected to an arm I98, which in turn is connected through a link I99 (Fig. 3) to a rock arm 200 having a pin 20I extending into a "slot 282 in a cam plate 203. The rock arm 200 is pivoted on the bed 10 and the cam plate 203 is mounted on a slide plate 205 (Fig. 4) vertically movable on adove-tailed guideway 208 secured to the face of the bed 10.

Upward movement of the slide plate 206 by mechanism to be described causes the cam plate 203 to move the rock arm 200 and shift the link I99 in the direction of the arrow a in Fig. 3. This in turn moves the arm I88 and rock arm I86 in a direction to depress and open the poppet valve I90 (Figs. .16 and 31) and to permit simultaneous closing of the poppet valve I9I by its spring I93.

The valves I90 and I9I are then in a position which is the reverse of that shown in Fig. 31, and the pressure supply pipe I65 (Fig. 31) is then connected through the chambers I86 and I85 to the pipe I84 and through the passage I83, cross passage I63 and port I6I to the left-hand end of the cylinder I40 of the reversing valve mechanism R.

As the right-hand end .of the cylinder I40 is always supplied with pressure 011. through the pipe I 64, both ends of the cylinder are then under equal pressure and the bobbin I will remain in whatever position it happens to occupy until one or the other of the poppet valves I12 or I18 are opened to reduce the pressure in the associated end of the cylinder I40.

If the piston MI is in the position shown in Fig. 31 and the poppet valve I12 is open, the pressure pipe I64 will be connected through the pipe I10, casing HI and port I 14 to the exhaust pipe 115, thus reducing the pressure in the cross passage I62 and in the right-hand end of the cylinder I40.

As full pressure is still maintained in the lefthand end of the cylinder, the piston .I4I will be shifted to the right, connecting the port I41 to the port I43 and thus admitting oil under pressure through the pipe 19 to the left-hand end of the main cylinder 11 The piston I will remain at the right-hand end of the cylinder I40 until the poppet valve I18 is opened, whereupon the pressure in the lefthand end of the cylinder I40 will be reduced and the piston I H will return to the position shown in Fig. 31, with oil under pressure supplied through the ports I41 and I42 and pipe 18 to the right-hand end of the main cylinder 11.

The connections between the dogs I13 and I19 and the poppet valves I12 and I18 will now be described.

Manual and automatic control of table travel A reversing lever 2I0 (Figs. 6 and 7) is loosely mounted on a shaft 2I I, which in turn is supported in a bearing in the slide plate 205. A downward projection of the lever 2I0 terminates in a ball-shaped end 2I2 positioned between the heads of the poppet valves I12 and I18. The lever 2I0 also extends upwardly to provide a handle 2I3 and a rearward projection 2 (Fig. 6) of the lever 2 I supports oppositely disposed lugs 2 I and 2I6, having downwardly inclined outer faces positioned for engagement by the dogs I13 and I19 respectively.

A handle 220 is connected to the front end of the shaft 2 and a lifting cam 22I (Figs. 3, 5,

and 8) is secured to the rear end of the shaft 2I I. The cam 22I cooperates with a cam opening in plate 206 fixed to the front of the bed 10.

By swinging the handle 220 upward toward vertical position, the cam 22I is moved in a clockwise direction as indicated in Fig. 5 and the slide plate 206 is moved upward. Such upward movement acts through the rock arm 200 and link I 88 to shift the poppet valve control mechanism P as previously described and place the machine in condition for operation.

The upward movement of the slide plate 286 also lifts the lugs 2I6 and 2I6 into the path of travel of the dogs I13 and I18. It is of course understood that these dogs, as well as the dogs I29 and I30 previously described, are all conveniently adjustable lengthwise of the sliding table 15 and that they may be secured in adjusted position by bolts 226 for the dogs I28 and I30 and by handle nuts 226 for the dogs I13 and I19.

The dog I13 (Figs. 6 and 7) is pivoted at 221 to an adjustable support 228 and has a projection 229 engaging an abutment 230 on said support. The dog I13 thus swings freely in a clockwise direction but is rigidly held from movement in the opposite direction. This permits a run-ofl of the table 16 to the left beyond the position determined by the dog I13, when desired.

The operative faces of the dogs I13 and I19 are also beveled or inclined to correspond to the bevel of the lugs 2I6 and 2I8.

The sliding table 16 is preferably provided with an upwardly extending wall 236 (Figs. 23 and 24) enclosing the head and tail stocks and protecting the mechanism from grinding wheel dust. A shelf 236 (Fig. 2) may be mounted on the front side of the table wall 235 for the con-' venience of the operator. A supply pipe 231 (Fig.

31) extends from the reservoir S to the pump P. Operation between tail and head centers 80 and 8| and positioned for engagement by a grinding wheel W.

In Fig. 32 the parts are shown just after a fresh tap has been inserted,the tap being loosely positioned angularly by the dog 92. The tap is then raised to the level of the wheel, as indicated I in Fig. 33, and the sliding table is moved to the right, carrying the work under the wheel.

The table is then reciprocated, as indicated by the double arrow in Fig. 34, and the work is raised very slightly during the grinding operation until the desired polished surface is attained.

The work is then lowered and removed to the left, as indicated in Fig. 35, in which position the tap is indexed, after which the described operations are repeated, this procedure being followed until all'flutes of the tap are ground.

Major adjustments of the work vertically are accomplished by use of the handle 56 (Figs. 18 and 19) after the toothed plate 6| has been withdrawn from engagement with the gear 52 by rocking the handle 69. The raising and lowering of the work during the grindingoperation, as described in connection with Figs. 32 to 35, is accomplished by swinging the arm 51 (Figs. 18 and 19).

The reciprocating motion of the table is under the control of the manually operated handle 220 (Fig. 4) and cam 22I (Figs. 3 and 5) by which the plate 205 and reversing lever 2I0 are raised or lowered.

When the plate 205 is raised, the cam slot 202 reverses the position of the rock arm I88 forming part of the poppet valve control mechanism P, which action opens the valve I and closes the valve ISI' (Fig. 31). This supplies oil under pressure through the pipe I84 to the left-hand end of the reversing valve cylinder 0, all as previously described.

Oil under pressure is thus supplied at both ends of the floating piston or bobbin I and the piston Ml moves toward one end or the other of the cylinder as one or the other of the poppet valves 112' and H8 is opened to relieve the pressure on the associated end of the cylinder H0.

The lifting of the slide plate 205 not only brings the lugs 215 and 216 on the reverse lever 2l0 into the path of movement of the dogs "3 and H9, but by reason of the inclined surfaces on the lugs and associated dogs, the lengthof stroke of the sliding table 15 and the travel of the work supported thereon is also controlled by the extent of lifting action.

By swinging the handle 220 through a greater or less arc, the cam 22| will lift therslide plate 265 a greater or less distance and the dogs I10 and I19 will engage wider or narrower portions of the lugs M5 and 2H5 on the reverse lever M0.

The higher the reverse lever and lugs are positioned, the longer will be the travel of the table in both directions. This manual control of table travel is of particular advantage in a machine for grinding flutes, as the flutes in different taps vary slightly in length and it is desired to grind each flute far enough to provide a bright surface but not far enough to force the wheel into solid metal. By operating the lever 220 with one hand and the lever 51 with the other hand, the operator can easily control both the depth and length of the cut, so that an effective grinding operation is quickly performed.

When the slide plate 205 is lowered at the end of the grinding operation, the poppet valve con trol mechanism P is returned to initial position and shifts the valves I90 and I9! to the position shown in Fig. 31 with the pipe I 84 connected to the exhaust.

The floating piston I will be immediately shifted to the left in Fig. 31, connecting the pipe 18 to the pressure supply and moving the table 15 to the left until further travel is prevented by a stop collar 240 on the piston rod I6.

Near the end of this left-hand travel, the dog I30 engages the arm I28 of the index mechanism, shifting the position of the valve disc I20 (Figs. 27 to 30) and effecting the indexing of the work.

As the table 15 completes its left-hand travel, an abutment 228 (Fig. 7) engages the rearward projection 2 on the reverse lever 2 l0 and swings the lever anti-clockwise to open the poppet valve I12 (Fig. 31). This relieves the pressure on the right-hand end of the piston I, so that the piston will move immediately to the right as soon as the control mechanism P admits pressure oil to the pipe I84.

When the slide plate 205 and reverse lever 2) are lifted to effect resumption of grinding operations, the lugs 215 and H6 will be at the right of the dog I13, but the dog will yield 'to permit passage of the lugs as the table moves to the right, which movement is immediately initiated as above described.

As previously stated, the rate of travel of the table 15 may be manually controlled by the speed control valve l5l shown in Figs. 13 to 15, and this valve when once set commonly does not require further attention unless a change in class of work takes place.

Having thus described our invention and the advantages thereof, we do not wish. to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what we claim is:-

l. In a grinding machine. a sliding table, table-moving mechanism, a single control device for said mechanism, table-reversing means, and

manual means to move said device toward and away from the path of table movement, said device when moved by said manual means toward said path placing said machine'in operation and said device when additionally moved by said manual means in the same direction being effective to change the range and extent of working travel of said table as defined by said reversing means and during a grinding operation.

vice is movably mounted, said support being normally in lowered inoperative position, and manual means to raise said support and to thereby move said device into the path of travel of said dogs.

4. In a grinding machine, a sliding table, dogs on said table, hydraulic table-moving mechanism, a control and reverse device for said mechanism, a support for said device, means to lower said support so that said device will clear the dogs, and table-stopping means controlled by said lowering movement.

5. In a grinding machine, a sliding table, a

pair of associated reversing dogs on said table, table-moving mechanism, a control and reverse device for said mechanism normally out of position to engage either of said dogs, means to move said device into position for alternate engagement by both of said dogs, and automatic means to immediately move said table to reloading position, and stop said table in such position whenever said device is moved out of operative relation to both of said dogs and regardless of the direction of travel of the table when said device is so moved. 6. In a grinding machine, a sliding table, dogs on said table, hydraulic table-moving mechanism, a control and reverse device for said mechanism, a support for said device, means to lower said support so that said device. will clear the dogs, a valve device effective to cause the table to move to reloading position, and a control connection between said support and said valve device.

7. In a grinding machine, a sliding table, dogs on said table, hydraulic table-moving mechanism, a. control and reverse device for said mechanism, a support for said device, means to lower said support so that said device will clear the dogs, a valve device effective to cause the table to move to reloading position, a control connection between said support and said valve device, and a cam on said support acting to shift said control connection as said support is lowered.

8. In a grinding machine, a sliding table, dogs on said table, hydraulic table-moving mechanism, a control and reverse device for said said device being alternately engaged and moved by said dogs, means effective to vary the extent of working travel of the table resultant from alternate engagement of said device by said dogs while the portions of said dogs which engage said device maintain a fixed relation to said table, and means continuously under manual controleifectivetooperatesaidflrstmeans to selectively vary the table travel while the machine is performing a grinding operation on a piece of work.

9. In a grinding machine, a sliding table, dogs on said table, table moving mechanism, a control and reverse device for said mechanism, said device being alternately engaged and 'moved by said dogs, and'm'anual means to shift said device bodily relative to said dogs and transversely of their path of travel and to thereby vary the extent of working travel resultant from engagement of said deviceby said dogs.

10. In a grinding machine, a sliding table, dogs on said table, table-moving mechanism, a control and reverse lever for said mechanism, and means to shift said lever vertically, said dogs having lever-engaging surfaces slanting down wardly toward each other, whereby the range of table travel is determined by the vertical position of said lever.

11. In a grinding machine, a sliding table, a hydraulic table moving mechanism, a reversing valve device therefor, -a pressure supply, and a manually operated control mechanism effective to expose both ends of said reversing valve device to full pressure during the time that the machine is in operation andalso effective to maintain full pressure at one end of said valve device and to simultaneously connect the other end of said device to the exhaust to relieve the pressure thereon at any point in the table travel and to thereby effect movement of said valve device by which said table is caused to move to predetermined initial position and to stop in such position.

12. In a grinding machine, hydraulic tablemoving mechanism, a reversing valve device therefor, a pressure supply and a control mechanism effective to connect both ends of said reversing valve device to said pressure supply during the time that the machine is in operation, and means to connect the pressure connection at one end or the other of said reversing valve to the exhaust at each end of table travel and thereby partially reduce the pressure at the corresponding end of said reversing valve andeffect reversal thereof.

13. In a grinding 'machine, hydraulic table-- -moving mechanism, a reversing valve device therefor, a pressure supply continuously connected to both ends of said valve device while the machine is in operation, a relief valve for each end of said cylinder, exhaust connections for said relief valves, and means to open a selected relief valve at each end of the table travel to effect reversal of said travel.

14. In 'a grinding machine, hydraulic tablemoving mechanism, a reversing valve device therefor, apressure supply continuously connected to both ends of said valve device while the machine is in operation, a relief valve for each end of said cylinder, exhaust connections for said relief valves, means to open a selected relief valve at each end of the table travel to effect reversal of table travel, and means to shift the connection at one end of said valve device from pressure to exhaust when the machine is to be stopped and to thereby cause the machine to be stopped in I reloading position.

15. In a grinding machine, a frame, a worksupporting member, a lifting screw for said member, a cross shaft geared to said screw, a gear fixed to said cross shaft, an arm loose on said cross shaft, a handle on said arm, a driving element on said arm engaging said gear, and a connection between said driving element and said handle whereby said driving element may be moved to inoperative position by rocking said handle on said arm. I

16. The combination in a grinding machine as set forth in claim 15, in which a second gear engages the gear on the cross shaft, and a second arm and handle are connected to turn said second gear, said second arm and handle being available for major vertical adjustments of said member.

STANLEY W. BATH. ERVIN L. ACKLEY. 

